This.
Those who book the "Wishes Dessert Party" in advance are seated at Tomorrowland Terrace tables,
in the order that they show up and check in. (Boo!)
Those who wait to book the "Wishes Dessert Party" on the "day-of" are given passes to the East Hub viewing area.
(Yes, they are now offering MORE availability to the "Wishes Dessert Party" due to
the increased space at the East Hub viewing area.)
Everyone dines on their desserts inside the Tomorrowland Terrace restaurant.
(Reports say that there are two separate serving areas for desserts.)
Of those who booked in advance, if there are some who want to go to the East Hub viewing area,
they will be allowed to do so, up to the point that the East hub viewing area is "full."